Allow nesting of conditional statements

[EyMaddis]

I noticed that nesting multiple IF-Statements is not supported and since I have to handle multiple target platforms while also checking for environment variables (like production mode) nesting support would help a whole lot. Right know I have to have unnecessary code duplications in my files and other workarounds.

Thanks

[Frizi]

First nested directives support was added in 9644439ba48262e89c027fbe9d63f8292efd954e, and later a few fixes were added to it. All of that landed in 3.0.0. Neting should work out of the box. Make sure you are using current version of the tool.

[zwacky]

I ran into the same thing as well, using preprocess 3.1.0.